In certain applications, such as the installation of wind turbines or other elevated equipment, it is common the use of supporting towers that can be made in different materials, usually metal or concrete.
The building processes of both kind of towers are different, as in the case of metal towers, they are built upon cylindrical or conical tubes, while concrete towers can be built from prefabricated parts that are conveniently assembled or are built onsite by using formwork elements to define the shape of the tower and build it by sections, by pouring concrete into the formwork.
Although they are built differently, all existing typologies share a geometrical characteristic, which is that their outer and inner surfaces are mathematically continuous surfaces. Such continuity facilitates attachment of a piece of steel to another, or of a concrete element, either onsite or in a prefabricated way. This feature has defined the geometries of every tower executed until today, including: cylindrical, conical or parabolic shaped towers, either with polygonal sections and/or with mixed polygonal-curved sections.
In the construction work for vertical structures, building systems comprising individual panels that are joined together to form a formwork into which concrete is poured are used. In the case of tall vertical structures, the formwork is made at different stages, using for this the climbing system consisting of uninstall the formwork panels that are situated at lower heights and to install them at an immediately superior height to make the formwork in this new dimension and build an additional tower section, repeating the process until the desired overall height is reached.
As it is known, in the climbing formwork system the panels are mounted on racks or scaffold units which are anchored at the top of the already made section by means of climbing cones. The elevation of the formwork elements from one level to another can be performed using a crane or, in the so-called self-climbing systems, using mechanical or hydraulic lifts.
The construction of concrete structures of constant cross-section, for example cylindrical or prismatic, allows the use of the same panels to conform the formworks for successive sections or levels of the tower; however, the construction of concrete towers or structures of varying cross-section requires the use of formwork panels of different shapes and curvatures for each level or section of the tower to be built. This makes it necessary to have a very large number of formwork panels that must be sufficient to cover the entire surface of the tower to be built, as well as the handling and storage of a large amount of material, which ultimately increases the cost of the work.
It is noteworthy that there are also formwork panels on the market for the construction of conical towers that allow for adjusting their curvature before being assembled and secured; however, this adjustment is particularly difficult, especially when any of the panels has undergone any deformation.
In document WO 03/069099 is described a wind turbine tower consisting of reinforced concrete prefabricated pieces, which are placed next to each other to form a tower of circular or polygonal cross-section.
In document GB 797 413 a cooling tower is described, which is built of prefabricated pieces of concrete or other material, arranged so that together they make up the required shape.
Document CA 1 245 877 relates to a domed construction which is frameless supported and constructed by precast elements joined together.
Document FR12954563 describes a formwork for the construction of cones or truncated pyramids, which includes angle panels of non-parallel sides and intermediate panels in the shape of regular trapezoids arranged between the angle panels, and which is moved at a different speed than those in the formwork of successive sections of the tower, providing a variation of the separation between the side panels.